Device for driving a shaft in rotation

ABSTRACT

A device for driving a shaft in rotation, of the kind comprising at least one set of two identical rotary jacks mounted on a common shaft, the annular space comprised between the cylindrical casing of each jack and the shaft coaxial with this latter being divided into two fluid-tight chambers of variable volume, separated on the one hand by a longitudinal abutment provided on the internal face of the said cylindrical casing, and on the other hand by a radial blade fixed longitudinally in the said shaft, the cylindrical casing of each jack being provided with a device for locking it with respect to a housing by which said casing is enclosed. It comprises: a hydraulic circuit composed of two portions connected to a common tank; a first portion supplied by a main pump and a second portion supplied by a topping-up pump; the locking device of the cylindrical casing of one jack being constituted by a cylindrical housing enclosing the jack casing and comprising a fluid-tight annular chamber, in which the wall in contact with the outer surface of this same casing is a thin wall, the said annular chamber being connected by means of a three-way distributor with two positions, either to the said main pump or the the common tank.

United States Patent Valantin 51\ June 20, 1972 DEVICE FOR DRIVING ASHAFT IN ROTATION Inventor: Alfred Valantin, Clermont, France Assignee:Charbonnages De France, Paris, France Filed: Oct. 13, 1969 Appl. No.:865,918

Foreign Application Priority Data Oct. 15, 1968 France ..68170022 US. Cl..91/167, 92/121, 92/52 Int. Cl. ..FlSb 11/18, FOlb 7/20, FOlc 9/00Field ofSearch ..91/167, 167 A; 92/121 References Cited UNITED STATESPATENTS Floer ..9l/167 Primary Examiner-Martin P. Schwadron AssistantExaminer-Clemens Schimikowski Att0rney Karl W. Flocks [57] ABSTRACT Adevice for driving a shaft in rotation, of the kind comprising at leastone set of two identical rotary jacks mounted on a common shaft, theannular space comprised between the cylindrical casing of each jack andthe shaft coaxial with this latter being divided into two fluid-tightchambers of variable volume, separated on the one hand by a longitudinalabutment provided on the internal face of the said cylindrical casing,and on the other hand by a radial blade fixed longitudinally in the saidshaft, the cylindrical casing of each jack being provided with a devicefor locking it with respect to a housing by which said casing isenclosed.

It comprises: a hydraulic circuit composed of two portions connected toa common tank; a first portion supplied by a main pump and a secondportion supplied by a topping-up pump; the locking device of thecylindrical casing of one jack being constituted by a cylindricalhousing enclosing the jack casing and comprising a fluid-tight annularchamber, in which the wall in contact with the outer surface of thissame casing is a thin wall, the said annular chamber being connected bymeans of a three-way distributor with two positions, either to the saidmain pump or the the common tank.

6 Claims, 16 Drawing Figures 'PATENTEDJuu20 m2 3.670.627

sum 1 or i FIG. 70

INVENTOR ALFRED VALANTIN ATTORNEY PATENTEOJuu2o m2 3,670,627

smear an? 1 PATENTEnJuxzo I972 3,670,627

SHEET 7 BF 7 FIG. 5b

FIG. 6C

FIG. 6e

DEVICE FOR DRIVING A SHAFT IN ROTATION The present invention relates toa device for driving rotary jacks in continuous or almost continuousrotation for the production of high torques, especially applicable tothe production of motors intended to supply a high power with an overallsize which is as small as possible.

Rotary jacks are already known from which there is obtained a movementof rotation at high torque, these generally comprising a hollowcylindrical casing known as the stator, and being provided with alongitudinal internal abutment mounted on a shaft having the same axisin which is fixed a blade de-limiting two fluid-tight chambers comprisedbetween a lateral face of the blade and a lateral face of the abutment,each chamber being alternatively put under pressure and under depressionin order to obtain alternately the rotation of the shaft and rotation ofthe cylinder, the above cylindrical casing being alternately locked andreleased with respect to a casing which encloses it.

Jacks of this kind do not however provide the possibility of obtaining alarge angle of rotation of the shaft at each cycle, the value of thisangle being always less than one revolution, and the utilization ofthese jacks involves a substantial proportion of dead time.

The present invention avoids these drawbacks by providing a devicegiving the possibility of obtaining rotation of a shaft through a muchgreater angle and even continuous rotation, thereby practicallyeliminating the dead times inherent in conventional rotary jacks.

The device according to the invention, of the kind comprising at leastone group of two identical rotary jacks mounted on a common shaft, theannular space comprised between the cylindrical casing of each jack andthe shaft coaxial with this latter being divided into two fluid-tightchambers of variable volume, separated on the one hand by a longitudinalabutment arranged on the internal face of the said cylindrical casing,and on the other hand by a radial blade fixed longitudinally in theshaft, the cylindrical casing of each jack being provided with a devicefor locking it with respect to the housing, is characterized in that itcomprises a hydraulic circuit composed of two parts coupled to a commontank, a first portion supplied by a main pump co-operating on the onehand with the first chamberof the first jack and the first chamber ofthe second jack, and further co-operating with the locking devices ofthe cylindrical casings of the jacks, and a second portion supplied by atopping-up pump cooperating with the second chamber of the first jackand the second chamber of the second jack, these two chambers beingcoupled in parallel to the said topping-up pump and members forreversing the direction of circulation of the fluid between thecorresponding chambers of the two jacks, cooperating through theintermediary of a control distributor with the elements of the hydrauliccircuit, the locking device of the cylindrical casing of one jack beingconstituted by a cylindrical housing enclosing the said casing andcomprising a fluid tight annular chamber, in which the wall in contactwith the outer surface of this same casing is a thin wall, the saidannular chamber being connected by means of a three-way distributor withtwo positions, either to the main pump or to the common tank.

In accordance with other characteristic features:

in each jack, the longitudinal abutment of the cylindrical casing isprovided on one side with a control contact of a four-way distributorwith two positions, the said contact cooperating with the correspondingblade and the said distributor co-operating with two conduits connectedin parallel to the topping-up pump;

--The first portion of the hydraulic circuit comprises two valves forreversing the direction of circulation of the fluid in two conduitsconnected in parallel to the main pump and coupling this latter to thelocking devices of the jacks and coupling said jacks to the common tank,these two three-way distributors with two positions being alwayssimultaneously in positions contrary to each other, the control devicesof the said distributors co-operating respectively with the fluidcirculating in two conduits connected in parallel to the topping-uppump;

The first portion of the hydraulic circuit comprises a distributor forreversing the direction of circulation of the fluid between the firsttwo chambers of the two jacks, the said distributor having four ways andtwo positions, its control members co-operating respectively with thefluid circulating in the conduits connected in parallel between the mainpump and the locking devices of the jack.

According to an alternative form:

--A differential coaxial with each of the two jacks is interposedbetween them, the cylindrical casing of each of them being rigidly fixedto one of the two crown wheels of the said differential, its satellitepinions being fixed radially and uniformly spaced apart on the commonshaft, and engaging with the said crown wheels;

The corresponding chambers of the two jacks are coupled in parallel tocircuits which are themselves in parallel on the main pump, while thecircuit of the topping-up pump comprises only two branches in parallelconnected to the controls of the distributors for reversing thecirculation of the fluid in the conduits connecting the main pump to thelocking devices.

Other characteristic features and advantages of the invention will bemore clearly brought out in the description which follows below, givenby way of non-limitative example, reference being made to theaccompanying drawings, in which:

FIG. la represents a longitudinal cross-section of a pair of jacksaccording to the invention;

FIGS. lb and 1c show respectively the transverse sections of the saidjacks taken along the lines YY and Z--Z of FIG. la;

FIG. 2 shows the diagram of the hydraulic control circuits of the abovepair of jacks:

FIGS. 3a, 3b, 3c, 3d and 32 show diagrammatically the successive stagesof the operation of the pair of jacks;

FIG. 4 shows a longitudinal cross-section of another form ofconstruction of a pair of jacks according to the invention;

FIG. 5 represents the diagram of the hydraulic control circuits of thepair of jacks in the form of construction shown in FIG. 4;

FIGS. 60, 6b, 6c, 6d and 6e show diagrammatically the successive stagesof the operation of the pair of jacks in the form of construction shownin FIG. 4.

Referring now to FIGS. la, 1b and 1c, the device according to theinvention comprises a set of jacks A and B mounted on a common shaft 1,comprising two cylinders 2a and 2b coaxial with the shaft 1 and forminga fluid-tight annular chamber between their internal longitudinal andtransverse walls and the outer wall of the said shaft. Each of thecylinders 2a and 2b comprises a longitudinal abutment 3a (and 3b),directed parallel to a generator line arranged from one transverse wallto the other, the internal face of which is in fluid-tight contact withthe shaft 1. In each of the parts of this shaft corresponding to theinterior of the above cylinders, there are fixed radial blades such as4a and 4b, the end faces of which are in moving and fluid-tight contactwith the corresponding longitudinal inner faces of the cylinders 2a and2b, and the transverse faces are also in moving and fluid-tight contactwith the inner transverse faces of the said cylinders.

The annular space located between the shaft 1 and each of the cylinders2a and 2b is thus divided by the abutment and the corresponding radialblade into two fluid-tight chambers such as C and C in the cylinder 2aand C and C in the cylinder 2b, and the volume of which varies when theabutment and the blade are in relative movement with respect to eachother, the total volume of the two corresponding cham bers remainingconstant.

The assembly formed by the cylinders 2a and 2b is enclosed by a commonhousing 5 comprising, facing each of the said cylinders, a closedannular space or chamber C or C separated from the outer face of thecorresponding cylinder by a thin wall 5a or 5b; when one of thesechambers is filled with a fluid under pressure, the thin wall produces abindinghoop efiect on the corresponding cylinder and immobilizes it.Referring now to FIG. 2, the hydraulic circuit for driving the shaft 1in rotation comprises a first portion, shown in thick lines, whichcomprises a main high-pressure pump PP coupled by the conduit to thechamber C of the jack A and by the conduit 11 to the chamber C of thejack B, and is coupled to the chambers C and C respectively by theconduits l2 and 13, the conduits l4 and permitting the coupling to thetank B of the chambers C and C through the intermediary of hydraulicdistributors HV and HV respectively, each of the type with three waysand two positions, these latter being shown symbolically by therectangles a and b respectively, the rectangle a of the distributor HVputting the pump PP in communication with the chamber C and itsrectangle b putting this same chamber into communication with the tankB, while the rectangle a of the distributor HV establishes theconnection between the pump PP and the chamber C and its rectangle b theconnection between this same chamber and the tank D.

A distributor l-IV of the type with four ways and two positions 0 and band the movement of which is controlled by appropriate devices known perse, actuated by the fluid pressure supplied to the said devices by theconduits l6 and 17, respectively branched on the conduits 12 and 13, isarranged on the pair of conduits 10 and 11 so as to permit reversal ofthe direction of circulation of the fluid between the chambers C and C.

This first conduit is completed by a pressure-limiting device 18,calibrated to a pressure P, mounted between the outlet of the pump PPand the tank, and by a pressure-limiting device 19 calibrated to a valuep less than P, mounted between the return circuit of the said pump andthe tank D.

The second part of the hydraulic circuit, shown in lines of normalthickness, comprises a topping-up pump PG connected on the one hand tothe tank D and on the other hand coupled by the conduits 20 and 21,branched on the common conduit 22, respectively, to the chambers C ofthe jack A and C of the jack B. The conduit 22 may be connected to thecontrol device of the distributor HV by means of the conduit 23, or tothe control device of the distributor HV by means of the conduit 29,through the intermediary of the distributor l-[V of the type with fourways and two positions a and b, the position b enabling the topping-uppump to be put into communication with the control of the distributor HVthrough the intermediary of the conduits 22 and 23, and permits thecontrol of the distributor I-iV to be put into communication with thetank D through the intermediary of the conduits 24 and 25, the positiona permitting the topping-up pump to be put into communication with thecontrol of the distributor HV through the intermediary of the conduits22 and 24 and also the control of the distributor l-IV to be put intocommunication with the tank through the intermediary of the conduits 23and 25.

The distributors HV and HV are identical and are displaced into positiona by the effect of the pressure applied by the fluid on their control,and are returned to position b by a spring R when the effect of thispressure ceases. The distributor HV is of the latching type withmechanical control; its movement from position a to position b isobtained by means of the hydraulic end-of-travel contact FC,, placed oneach of the abutments 3a and 3b, actuated by one or the other of theblades 4a and 4b arriving at the end of its travel against thecorresponding abutment. This second part of the hydraulic circuit iscompleted by a pressure-limiting device 26 interposed between the tankand the outlet of the topping-up pump in order to protect this latter,and is calibrated to a pressure P,. In addition, a non-retum valve 27,calibrated to a pressure A p is interposed between the return of themain pump PP and the topping-up pump PG.

in the FIG. 2 there has been shown the position of the whole of thedevice when the distributor HV occupies the position b. Under theseconditions, the distributor HV the control of which is under pressure,permits the passage of the fluid under pressure sent by the pump PP intothe conduits l2 and 16, which has the effect of maintaining the chamberC under pressure and immobilizing the cylinder 2a, and of pushing ormaintaining the distributor HV in the position a while the distributorHV is in the position b, its control being under depression, which hasthe effect of putting the conduit 13 and therefore the chamber C underdepression, together with the conduit 17.

The passage of the distributor HV to the position a has the effect ofputting the conduit 24 under pressure and in consequence to cause thedistributor HV to pass to the position a and to put under depression theconduit 23 and in consequence to cause the distributor HV to pass intothe position b. The conduits 12 and 16 are then under depression whilethe conduits 13 and 17 are under pressure for this reason, the cylinder2b is immobilized while the cylinder 2a is freed and the distributorl-lV is pushed from the position a to the position b.

Under these conditions, and referring to FIGS. 2, 3a, 3b, 3c, 3d and 3e,the operation of the whole of the device is as follows: the jacks A andB being assumed to be simultaneously and respectively found in theconditions shown in FIGS. 3a and 3b, for which the end-of-travel contactPC, has just been actuated by the blade 4b of the jack B and occupiesthe position b, the main pump PP and the topping-up pump PG being alsoassumed to be in operation, the distributor l-lV operated by the contactPC, into the position a drives in its turn the distributor I-IV into theposition a. The fluid contained in the chamber c of the jack A beingthen put under pressure, the thin wall 5a is deformed and holds thecylinder 2a immobilized, while the chamber C is supplied with fluidunder pressure. Under the effect of the thrust applied to the blade 4a,the shaft 1 common to the two jacks A and B is then driven in rotationabout its axis X-X. The speed of rotation to of the said shaft and thetorque which is applied to it depend on the dimensions of the blade, onthe pressure and on the flow-rate Q of the fluid injected by the pumpPP.

The blade 4b of the jack B is then driven by the shaft 1 at a speed ofrotation which, with respect to a fixed reference point, has also thevalue or while the cylinder 2b is in turn driven in rotation about theaxis XX at a speed m at least equal to 2W with respect to the same fixedreference point. In fact, the fluid stored in the chamber C is deliveredinto the chamber C as and when the volume of the chamber C,,, increases,the delivery flow-rate having in consequence at each instant, the samevalue Q as the flow-rate of supply of the fluid under pressure to thechamber C,,,, while the topping-up pump PG supplies a supplementaryquantity of fluid with a flow-rate q to the chamber C The pressure ofthe fluid in the chamber C equal to p1, is greater by A p than thepressure p of the fluid in the chamber C. For this reason, the abutment3b and in consequence the cylinder 2b is driven in rotation about X-X'with respect to the blade 4b at a speed at least equal to a); as thesaid blade is itself driven in rotation with respect to the fixedreference point at a speed 01, the speed of the cylinder 2b with respectto the fixed reference point, that is to say its absolute speed, isactually equal to at least 20).

As the abutment 3b of the cylinder 2b of the jack B rotates faster thanthe blade 4b, it comes up with the latter before the blade 4a of thejack A has completed its travel (see FIG. 30), and then moves at thesame speed as the blade 4b until the blade 4a has completed its course,thus being located in the same relative positions as at the outset. Whenthe blade 4a completes its travel (see FIG. 3d) it actuates theend-of-travel contact PC on the abutment 3a, which has the effect ofplacing the corresponding distributor in the position a and inconsequence of causing the release of the cylinder 2a by putting thechamber C into communication with the tank through the intermediary ofthe distributor HV, passed into the position b, of causing the lockingof the cylinder 2b of the jack B, due to the fact that the fluid isunder pressure in the chamber C put into communication with the mainpump PP, through the intermediary of the distributor HV which has passedinto the position a. The jack B is then in the condition in which thejack A was placed at the beginning of the cycle and vice versa. Thecycle then continues, the jack B carrying out the same function as thejack A in the previous stage and conversely, and ensuring the rotationof the common shaft until the whole assembly is in the same condition asat the beginning of the cycle, after which a fresh cycle is started.

It is clear that instead of arranging a set of two rotary jacks on thesame shaft, it is possible to provide more, three or four for example,and thereby to increase the value of the torque available on the shaft.

Furthermore, in order to obtain rotation of the common shaft in bothdirections, it is only necessary to complete the hydraulic circuitdescribed above by two distributors of the same type as the distributorsl-IV and HV which have the purpose of changing-over the functions of theset of chambers C and C with the functions of the set of chambers C andC by a distributor of the same type as l-IV which ensures the switchingover of the movements of fluid between the chambers C and C and by adistributor ensuring the change over of the functions of the chambers Cand C In accordance with another form of embodiment, the rotary jackaccording to the invention differs from that previously described by theaddition of a differential interposed between the two elementary jacks Aand B. Referring now to FIG. 4, a jack of this kind is constituted bythe same elements as the jack shown in FIGS. la, lb and 10, but furthercomprises two conical toothed crown-wheels 6a and 6b respectively fixedto the cylinders 2a and 2b and arranged face to face as shown in FIG. 4,and also the conical pinions 7 engaging simultaneously with the toothedcrown-wheels 6a and 6b, and the axes of which are located in the sameplane, perpendicular to the axis X-X' and intersecting on this latter atthe point 0, the axes of the said pinions being uniformly spaced apartfrom the other. These bevel pinions, the number of which is suitablychosen and may be for example from one to six, pivot in the shaft 1 whenit is given a movement of rotation.

The hydraulic control circuit of a jack of this kind, shown in FIG. 5,is similar to that of the previous jack, but comprises a fewsimplifications with respect to this latter. In fact, the chambers C andC on the one hand and C and C on the other are respectively connected inparallel on the main pump PP, in such manner that when the chambers Cand C are simultaneously under pressure, the chambers C and C aresimultaneously under depression and vice versa, the changing over of thefunctions being effected by means of the distributor HV,. In this way,the non-return valve can be eliminated, since the over-pressure Apnecessary in the previous case for the driving in rotation of that ofthe two cylinders 2a which is mobile, is no longer necessary. Inconsequence, the pressurelimiting device 26 can also be dispensed with.

Under these conditions, the operation of the jack, illustrated by thediagrams of FIGS. 6a, 6b, 6c, 6d and 6e is as follows:

As the distributor l-IV actuated by the end-of-travel contact FC hasjust taken-up the position b (see FIG. 5), the distributor I-IV actuatedby I-IV is placed in its turn in the position a, which has the effect ofputting the distributor l-IV into the position a, and in consequence ofcausing the jack A to drive, since the chamber C is supplied with fluidunder pressure through the intermediary of the portion a of thedistributor HV and since the fluid has been put under pressure in thechamber C through the intermediary of the position a of the distributorl-IV the cylinder 2a being thereby locked.

The thrust which is applied on the blade 3a imparts to the shaft 1 aspeed of rotation W with respect to a fixed reference point, and also atorque, the value of this speed and this torque being, as previously, afunction of the dimensions of the blade, of the pressure and of theflow-rate of the fluid utilized. The blade 3b is then driven in rotationby the common shaft 1 at the same speed W as the blade 3a with respectto the same fixed reference as above, but the crown-wheel 6a of thedifferential, coupled to the locked cylinder 2a has zero speed, and thepinions 7 driven by the shaft 1 in a movement of rotational drive aboutthe axis X-X at the speed W impart to the crown-wheel 6b, coupled to thecylinder 2b, a speed of rotation about the same axis X-X having a valueof 2W with respect to the fixed reference point.

During the course of this movement, the increase of the volume of thechamber C has the same value as that of the chamber C these two chambersbeing simultaneously supplied with fluid under high pressure, at thesame pressure and with the same flow-rate. For this reason, a thrust isproduced which, being supported on the blade 3b, is applied on thecylinder 2b through the intermediary of the abutment 4b and producesthere a torque of the same value as that which is applied to the blade4a of the jack A. This torque is transmitted through the intermediary ofthe crown-wheel 6b, to the pinions 7 which transmit it to the shaft 1 bytheir arbors.

In this way, perfect synchronization is obtained of the relativemovements of the cylinders 2a and 2b, respectively relative to theblades 4a and 4b, and there is transmitted to the common shaft 1 the sumof the torques developed by each of the jacks A and B.

When the blade 40 has just completed its travel (see FIG. 6c) andactuates the end-of-travel contact PC the corresponding distributorpasses from the position b to the position a, thus causing thechange-over of the distributor I'IV; from the position b to the positiona and in consequence that of the distributor HV, from the position a tothe position b, which has the effect, on the one hand, of locking thecylinder 2a, the fluid under pressure being admitted to the chamber C ofreleasing the cylinder 2b, the chamber C being put to the tank, and ofsupplying fluid under pressure to the chambers C and C and inconsequence of interchanging the functions of the jacks A and B, thecycle continuing as shown in the diagrams of FIGS. 6d and 6a until thewhole assembly is again returned to the initial condition shown in thediagram of FIG. 6a.

This second form of embodiment has the further advantage of slightlysimplifying the hydraulic circuit, and also that of permitting thecontinuous utilization of the torque supplied by the two jacks A and B.In addition, as this hydraulic circuit is perfectly symmetrical withrespect to the two jacks, in order to obtain the possibility of rotatingthe shaft I in both directions, it is only necessary to provide in thiscircuit two distributors which interchange the functions of the chambersC and C and which respectively couple the chamber C to the position b ofthe distributor I-IV and the chamber C to the position a of this samedistributor.

I claim:

1. A shaft driving arrangement comprising in combination: a shaft havingat least one set of two identical rotary driving members mountedthereon, said driving members being in the form of a first and a secondcylindrical casing in coaxial relationship around such shaft and beingseparated therefrom by an annular space, each of said cylindricalcasings having a longitudinal abutment on its inner face, said shafthaving a radial blade extending longitudinally thereof and cooperatingwith said longitudinal abutment to form first and second fluid-tightvariable volume chambers in said annular space, said chambers beingseparated on one hand by said longitudinalabutment and on the other handby said radial blade; a cylindrical housing enclosing each of saidcasings and including a pair of annular fluid-tight chambers each ofwhich has a thin wall portion in contact with the outer surface of oneof said casings, said annular chambers being selectively filled withfluid to lock said housing and one of said casings together so that asthe volume of the variable volume chamber is varied the shaft is driven;an hydraulic circuit for reversing the direction of circulation of fluidbetween corresponding chambers of the two driving members, said circuitcomprising a first portion and a second portion, a common tank for saidtwo portions of the hydraulic circuit, a main pump adapted to supplysaid first portion of the circuit, a topping-up pump adapted to supplysaid second portion of the circuit, and a three-way distributor devicewith two positions to alternatively connect one of said annular chamberseither to said main pump or to said common tank.

2. A driving device as claimed in claim 7, and further characterized by:

two conduits connected in parallel on said topping-up -a four-waydistributor device with two positions, adapted to co-operate with saidtwo conduits,

a control contact mounted on said longitudinal abutment and ensuring thecontrol of said distributor device with four ways and two positions,said contact co-operating with the corresponding said blade.

3. A driving device as claimed in claim 2, further characterized by:

two conduits connected in parallel on said main pump and connecting saidpump to said locking devices and connecting said devices to said commontank,

two distributors with three ways and two positions for reversing thedirection of circulation of the fluid in said two conduits connected inparallel on said main pump, said two distributors being alwayssimultaneously in contrary positions with respect to each other,

control devices for said reversing distributors, co-operating with thefluid circulating in said two conduits connected in parallel on saidtopping-up pump,

two further conduits connected in parallel on said main pump andconnecting said pump to said first chamber of said first casing and tosaid first chamber of said second casing,

a four-way distributor with two positions for reversing the direction ofcirculation of the fluid, mounted on said two other conduits,

control devices for said reversing distributor co-operating with thefluid circulating in said conduits connected in parallel between saidmain pump and said locking means,

a conduit in parallel on said topping-up pump coupling said latter pumpwith said second chamber of said first casing and with said secondchamber of said second casing.

4. A driving device as claimed in claim 7, and further,

characterized by:

-a differential gear interposed between said two driving memberscomprising: two toothed crown-wheels each rigidly fixed to saidcylindrical casing of one of said driving members,

--satellite pinions fixed radially and uniformly spaced apart on saidshaft and adapted to engage with said toothed crown-wheels.

5. A driving device as claimed in claim 4, and further characterized by:

two conduits connected in parallel on said topping-up --a four-waydistributor device with two positions cooperating with said twoconduits,

a control contact mounted on said longitudinal abutment and ensuring thecontrol of said four-way distributor device with two positions, saidcontact co-operating with said corresponding blade,

two conduits connected in parallel on said main pump and coupling saidlatter pump with said locking devices and coupling said devices to saidcommon tank,

two distributors with three ways and two positions for reversing thedirection of circulation of the fluid in said two conduits connected inparallel on said main pump, these two distributors being alwayssimultaneously in contrary positions with respect to each other,

-control devices for said reversing distributors co-operating with thefluid circulating in said two conduits connected in parallel on saidtopping-up pump,

two other conduits connected in parallel on said main pump and couplingin parallel said corresponding chambers of said two driving members, afour-way distributor with two positions for reversing the direction ofcirculation of the fluid mounted on said two other conduits,

control devices for said reversing distributor adapted to co-operatewith the fluid circulating in said conduits connected in parallelbetween said main pump and said locking devices.

6. A driving device as claimed in claim 7, and further characterized by:

a first calibrated pressure-limiting device mounted between said mainpump and said tank,

a second pressure-limiting device, calibrated to a value higher thanthat of said first pressure-limiting device and mounted between saidtopping-up pump and said tank,

-a non-retum valve mounted between said first and secondpressure-limiting devices.

1. A shaft driving arrangement comprising in combination: a shaft havingat least one set of two identical rotary driving members mountedthereon, said driving members being in the form of a first and a secondcylindrical casing in coaxial relationship around such shaft and beingseparated therefrom by an annular Space, each of said cylindricalcasings having a longitudinal abutment on its inner face, said shafthaving a radial blade extending longitudinally thereof and cooperatingwith said longitudinal abutment to form first and second fluidtightvariable volume chambers in said annular space, said chambers beingseparated on one hand by said longitudinal abutment and on the otherhand by said radial blade; a cylindrical housing enclosing each of saidcasings and including a pair of annular fluid-tight chambers each ofwhich has a thin wall portion in contact with the outer surface of oneof said casings, said annular chambers being selectively filled withfluid to lock said housing and one of said casings together so that asthe volume of the variable volume chamber is varied the shaft is driven;an hydraulic circuit for reversing the direction of circulation of fluidbetween corresponding chambers of the two driving members, said circuitcomprising a first portion and a second portion, a common tank for saidtwo portions of the hydraulic circuit, a main pump adapted to supplysaid first portion of the circuit, a topping-up pump adapted to supplysaid second portion of the circuit, and a three-way distributor devicewith two positions to alternatively connect one of said annular chamberseither to said main pump or to said common tank.
 2. A driving device asclaimed in claim 7, and further characterized by: -two conduitsconnected in parallel on said topping-up pump, -a four-way distributordevice with two positions, adapted to co-operate with said two conduits,-a control contact mounted on said longitudinal abutment and ensuringthe control of said distributor device with four ways and two positions,said contact co-operating with the corresponding said blade.
 3. Adriving device as claimed in claim 2, further characterized by: -twoconduits connected in parallel on said main pump and connecting saidpump to said locking devices and connecting said devices to said commontank, -two distributors with three ways and two positions for reversingthe direction of circulation of the fluid in said two conduits connectedin parallel on said main pump, said two distributors being alwayssimultaneously in contrary positions with respect to each other,-control devices for said reversing distributors, co-operating with thefluid circulating in said two conduits connected in parallel on saidtopping-up pump, -two further conduits connected in parallel on saidmain pump and connecting said pump to said first chamber of said firstcasing and to said first chamber of said second casing, -a four-waydistributor with two positions for reversing the direction ofcirculation of the fluid, mounted on said two other conduits, -controldevices for said reversing distributor co-operating with the fluidcirculating in said conduits connected in parallel between said mainpump and said locking means, -a conduit in parallel on said topping-uppump coupling said latter pump with said second chamber of said firstcasing and with said second chamber of said second casing.
 4. A drivingdevice as claimed in claim 7, and further characterized by: -adifferential gear interposed between said two driving memberscomprising: -two toothed crown-wheels each rigidly fixed to saidcylindrical casing of one of said driving members, -satellite pinionsfixed radially and uniformly spaced apart on said shaft and adapted toengage with said toothed crown-wheels.
 5. A driving device as claimed inclaim 4, and further characterized by: -two conduits connected inparallel on said topping-up pump, -a four-way distributor device withtwo positions co-operating with said two conduits, -a control contactmounted on said longitudinal abutment and ensuring the control of saidfour-way distributor device with two positions, said contactco-operating with said corresponding blade, -two Conduits connected inparallel on said main pump and coupling said latter pump with saidlocking devices and coupling said devices to said common tank, -twodistributors with three ways and two positions for reversing thedirection of circulation of the fluid in said two conduits connected inparallel on said main pump, these two distributors being alwayssimultaneously in contrary positions with respect to each other, -control devices for said reversing distributors co-operating with thefluid circulating in said two conduits connected in parallel on saidtopping-up pump, -two other conduits connected in parallel on said mainpump and coupling in parallel said corresponding chambers of said twodriving members, -a four-way distributor with two positions forreversing the direction of circulation of the fluid mounted on said twoother conduits, -control devices for said reversing distributor adaptedto co-operate with the fluid circulating in said conduits connected inparallel between said main pump and said locking devices.
 6. A drivingdevice as claimed in claim 7, and further characterized by: -a firstcalibrated pressure-limiting device mounted between said main pump andsaid tank, -a second pressure-limiting device, calibrated to a valuehigher than that of said first pressure-limiting device and mountedbetween said topping-up pump and said tank, -a non-return valve mountedbetween said first and second pressure-limiting devices.